The first revision of fuel-economy requirements in three decades is likely to give US carmakers even less incentive to build small, fuel-efficient minivans and sports utility vehicles.
The proposed standards, to be phased in between the 2008 and 2011 model years, will replace the single fuel-economy target for light trucks with six categories, based on vehicle size. Their main benefit would thus be felt on smaller vehicles.
At a time of growing calls for the US to reduce its dependence on imported oil, the plan has been criticised by environmental groups as a sop to the three Detroit carmakers General Motors, Ford Motor and the Chrysler division of DaimlerChrysler which dominate the market for the biggest, most fuel-hungry SUVs and pick-ups.
The light-truck standard is currently set at an average of 21.2 miles a gallon for each manufacturer's 2005 models and 22.2 miles for 2007 models. By applying a single standard to a manufacturer's entire fleet, it forces carmakers to sell a proportion of light, fuel-efficient vehicles to make up for bigger, less efficient SUVs and pick-ups.
Under the new rules, the standard for the smallest vehicles, covering less than 43 sq ft, will rise from 26.8 miles a gallon in 2008 to 28.4 miles in 2011, a 6 per cent increase. The target for vehicles of 65 sq ft or more will rise a more modest 4.4 per cent, from 20.4 to 21.3 miles a gallon.
The average fuel-consumption standard for cars, which are not affected by the proposed changes, is 27.5 miles a gallon.
Norman Mineta, transportation secretary, said the changes to the Corporate Average Fuel Economy regulations (Cafe) would “save gas and result in less pain at the pump for motorists without sacrificing safety”.
However, environmental groups pointed out that the Detroit “big three” lag their Asian rivals, notably Toyota and Honda, in introducing smaller “crossover” vehicles, which look like SUVs but are built on a car chassis. US carmakers have also been slower in introducing hybrid petrol-electric vehicles.
Brendan Bell, the Sierra Club’s associate Washington representative, described the proposed rules as an incentive for carmakers to build bigger vehicles that qualify for the least rigorous fuel-economy standards.
The targets “are so far below where we can go, given current technology”, Mr Bell said. “This isn’t the kick in the rear that the American auto industry needs to compete with the Asian manufacturers.”
Under the new rules, the average fuel consumption for minivans would be set at 23.3 miles per gallon.
Retail gasoline prices have risen to record levels in recent weeks, but American drivers have so far shown little inclination to cut consumptionT
Neither existing Cafe rules or the proposed changes apply to the heaviest SUVs, such as GM's Hummer and the Ford Excursion. The proposals will be open for public comments for 90 days, with the final rules due to be set by April.